Device for changings directions of light rays

ABSTRACT

When light rays (L 1 , L 2 ) from any arbitrary directions arrive at the surface of incidence (3) at one end of a main body (2) made of a transparent glass or plastic, they are successively totally reflected internally by opposite reflecting surfaces (5a, 5b) of the main body (2) such that an angle formed between each light ray and the perpendicular to the reflecting surface gradually approaches to a critical angle δ 0  and the light rays are taken out of the main body through light emerging surfaces (5a, 5b, 4). The light rays taken out of the main body (2) through the light emerging surfaces are given greater components in directions parallal to the longitudinal direction of the main body (2) than the incident light rays (L 1 , L 2 ). Therefore, light rays from all directions, incident to the surface of incidence (3), after being caused to pass through the main body (2), are given substantially equal directivities. Typically, the main body (2) is in the form of a wedge-shaped plate, a cone or a polyhedron. In practical use, a plurality of main bodies (2) are arranged in a parallel array to form a board-like assembly whose one surface is used as a light incidence surface.

This is a continuation of co-pending application Ser. No. 07/059,878filed on May 18, 1987, now U.S. Pat. No. 4,813,765 and PCT to P86/00489.

TECHNICAL FIELD

The present invention relates to a device for changing the directions oflight rays and, more particularly, to a device for receiving light raysfrom all directions and converting them into light rays within apredetermined range of direction.

BACKGROUND ART

In the case of utilization of light, such as sunlight, whose angle ofincidence gradually changes, in order to attain an effectiveutilization, a light source tracking device which is so controlled as topoint to the direction of incident light is needed.

When a light input or reception means is always maintained to point tothe direction of incidence of light by the light source tracking device,the incident light can be received in a most effective manner. However,as the angle of incidence of, for example, sunlight gradually changesaccording to the season of the year and from the sunrise to the sunset,an effective light source tracking device must necessarily becomplicated in construction and expensive and cannot be usedpractically.

The present invention has been made to overcome the above and otherproblems encountered in the prior art and has for its object to providea device for changing the directions of light rays, which is maintainedstationary in the case of receiving light rays whose angles of incidencevaries from time to time or light rays from any directions without theuse of a light source tracking device and which can convert them intolight rays within a predetermined direction range so as to facilitatethe utilization of the received light rays.

DISCLOSURE OF THE INVENTION

A device for changing the direction of light rays in accordance with theinvention has a three-dimensional body which is made of an opticallytransparent material and has a light incidence surface and a lightemerging surface. The main body has reflecting surfaces for causingrepetitive reflections of the light rays which have entered the bodythrough the light incidence surface. The reflecting surfaces of the mainbody are so arranged and shaped that the direction of a light ray whichis repeatedly internally reflected within the body is caused to have anangle incident on the reflecting surfaces, which gradually approaches acritical angle with respect to the reflecting surface. A portion of themain body or a portion adjacent to said first-mentioned portion at whichthe light rays are reflected at the critical angle or at an anglesmaller than the critical angle constitutes the light emerging surfacefrom which the light rays whose directions are changed are derived.

The light rays which has entered through the incidence surface of themain body into the same are repeatedly internally reflected and, becauseof the profiles of the reflecting surfaces, the angle of each reflectedlight ray relative to a perpendicular is gradually increased and becomesequal to the critical angle or an angle slightly smaller than thecritical angle. When reaching such condition, the light rays are notreflected internally by the reflecting surface any longer, but refractedat the reflecting surfaces, thus being emitted out of the main body.Since the light rays are incident to the reflecting surfaces at anglesclose to the critical angle, they are refracted at the reflectingsurfaces, being emitted from the main body. substantially at apredetermined angle relative to the reflecting surfaces or the outersurface of the main body or being emitted within a predetermined angularrange. As a result, the light rays emitted or emerging from the mainbody are almost in the same direction.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIG. 1 is a sectional view of a main body according to a preferredembodiment of the present invention;

FIG. 2 is a perspective view thereof;

FIG. 3 is a view explanatory of the mode of operation of the firstembodiment shown in FIG. 1;

FIG. 4 is a perspective view of an assembly for changing the directionsof light rays in which a plurality of main bodies as shown in FIG. 2 arearranged in a parallel array;

FIG. 5 is an enlarged view illustrating a portion indicated by V in FIG.4;

FIG. 6 is a view explanatory of the behaviors of light rays incident ona light incidence surface;

FIG. 7 is a sectional view of a device for assisting the incidence oflight rays;

FIG. 8 is a perspective view of a further preferred embodiment of thepresent invention;

FIG. 9 is a perspective view of a yet further preferred embodiment ofthe present invention;

FIG. 10 is a view explanatory of diverging angles of light rays emittedfrom a main body;

FIG. 11 illustrates auxiliary elements attached to the main body;

FIG. 12 illustrates modified auxiliary elements;

FIG. 13 is a partial view, on an enlarged scale, of FIG. 12;

FIG. 14 illustrate yet further auxiliary elements;

FIG. 15 is a partial view, on an enlarged scale, of FIG. 14;

FIG. 16A is a side view of an assembly for changing the directions oflight rays in which a plurality of main bodies as shown in FIG. 8 orFIG. 9 are assembled;

FIG. 16B is a perspective view of FIG. 16A;

FIG. 17A is a side view of a modification of the assembly shown in FIG.16A;

FIG. 17B is a perspective view of FIG. 17A;

FIG. 18A is a side view of a modification of the assembly shown in FIG.16A;

FIG. 18B is a perspective view of FIG. 18A;

FIG. 19 shows yet another preferred embodiment of the present invention;

FIG. 20 shows an example of a combination of the main bodies as shown inFIG. 1;

FlG. 21 is a view illustrating an embodiment of a "rotation" type devicein accordance with the present invention;

FIG. 22 is a view illustrating another embodiment of a "rotation" typedevice in accordance with the present invention;

FIG. 23 is a view illustrating a device for selecting the direction ofincidence adapted for use with the "rotation" type device in accordancewith the present invention;

FIG. 24 is a view explanatory of a phenomenon observed when a pluralityof main bodies are assembled into a parallel array as shown in FIGS. 4and 5;

FIG. 25 is a sectional view, on an enlarged scale, of a still furtherembodiment of a device for changing the directions of light rays inaccordance with the present invention; and

FIG. 26 is a sectional view, on an enlarged scale, of a yet furtherembodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

The preferred embodiments of the present invention will now bedescribed. The device for changing the directions of light rays shown inFIG. 1 has a main body 2 made of an optically transparent material suchas transparent glass, a transparent plastics or the like. The main body2 is, for instance, in the form of a plate of wedge-shaped cross sectionas shown in FIG. 2 and is gradually decreased in thickness from one sideto the opposite side. An end surface 3 on one side of the main body 2defines a light incidence surface, and a pair of opposing planes 5a and5b which are extended from the light incidence surface 3 to an endsurface 4 on the other side of the main body 2 define reflectingsurfaces on which light rays which have entered the main body 2 throughits light incidence surface 3 are reflected. The end surface 4 may bemade very small in area or eliminated.

When a light ray L₁ is sent to the light incidence surface 3 of the mainbody 2 in the above-described construction shown in FIG. 1, it repeatsinternal reflections at points a, b, c, d and e on the reflectingsurfaces 5a and 5b while propagating toward the end surface 4 and isfinally emitted out of the main body 2 at a point f. In like manner, alight ray L₂ incident from a direction different from the direction ofincidence of the light ray L₁ is repeatedly reflected internally at al,bl, cl, dl and el and is finally emitted out of the main body 2 at apoint fl. These internal reflections of the light rays L₁ and L₂ aretotal reflection.

Next the above-described phenomenon will be considered with reference toFIG. 3. It is assumed that the angle between each of the reflectingsurfaces 5a and 5b and the center surface (optical axis) 0--0 of themain body be a and that an internally reflected light ray be incident ata point P on the reflecting surface 5b. When the angle between theinternally reflected incident light ray and a perpendicular to thereflecting surface 5b at the point P is greater than a critical angleδ₀, the internally reflected light ray undergoes total reflection at thepoint P and is directed again to the opposing reflecting surface 5a. Onthe other hand, when the angle of incidence of the internally reflectedlight ray incident at the point P is equal to the critical angle δ₀, itis refracted and emerges parallel to and along the outer surface of thereflecting surface 5b at the point P. Furthermore, when the angle ofincidence of the internally reflected light ray is smaller than thecritical angle δ₀, it is emitted out of the main body 2 into thesurrounding medium at an angle X in relation to the perpendicular asindicated by the broken lines As described above, the angle of incidenceof a light ray striking the reflecting surface is small, the light rayis totally reflected at the reflecting surface and when the angle ofincidence is gradually decreased and becomes equal to the criticalangle, at least part of the light ray is refracted at the reflectingsurface and emitted out of the main body 2 into the surrounding mediumin parallel with the outer surface of the reflecting surface.Furthermore, when the angle of incidence is increased, it is refractedat the reflecting surface and emitted out of the main body 2 into thesurrounding medium.

When the material of the main body 2 has an index of refraction nl andthe atmosphere or medium surrounding the main body 2 has an index ofrefraction n2, the following relation is established.

    nl·sin(δ.sub.0 -Δδ)=n2·sinX

Meanwhile, whenever a light ray undergoes total reflection at thereflecting surface 5a or 5b, the angle of incidence of the totallyreflected light ray arriving at the opposite reflecting surface 5b or 5ais decreased by 2a so that the light ray incident at the reflectingsurface becomes more and more upright relative to the reflectingsurface, and when the angle of the light ray becomes smaller than thecritical angle δ₀, at least part of the light ray is refracted at thereflecting surface and emitted out of the main body to the surroundingmedium. It follows therefore that if an internal light ray is incidentat the point P at an angle smaller than the critical angle δ₀ by 2a andis refracted totally at the reflecting surface and emitted into thesurrounding medium as indicated by the broken lines in FIG. 3, thefollowing relation is established:

    nl·sin (δ.sub.0 -2a)=n2·sinX

When the surrounding medium is air, n2=1 and when X =90°-X, thefollowing relation is obtained:

    nl·sin(δ.sub.0 -2a)=sinX=sin (n/2-X)-cosX

Hence,

    X=cos.sup.-1 {(nl·sin(δ.sub.0 -2a)}

Therefore, when δ₀ -2a<n/2, the greater the value a, the greater thevalue X becomes.

If the light ray is refracted not totally and emitted out of the mainbody and the light ray is partly reflected again even when the angle ofincidence is smaller than the critical angle, the following relation isobtained:

    X=cos.sup.-1 {nl·sin(δ.sub.0 -4a)}

As a result, the value X is increased more and more.

As is apparent from the above explanation with reference to FIG. 3, thelight rays undergo total reflection at the points a, b, c, d and e andthe points al, bl, cl, dl and el as shown in FIG. 1 and when the anglesof incidence of the light rays become equal to or smaller than thecritical angle δ₀ for the first time at the points f and fl,respectively, the light rays are refracted and emitted out of the mainbody 2 to the surrounding medium The light rays are emitted out of themain body 2 also through its end surface to the surrounding medium.

When light rays from all directions are incident on the incidencesurface 3 and enter the main body 2 and when it is desired that thelight rays emitted from within the main body through the reflectingsurfaces 5a and 5b and the end surface 4 are in parallel or almost inparallel with the optical axis 0--0, it is preferable that the angle ais made as small as practicable, but when a is made small, the wholelength L will be increased (FIG. 2).

In order to overcome this problem, the thickness d of the lightincidence surface 3 (FIG. 2) must be reduced as much as possible.

When main bodies 2 having a thickness d made as small as possible areutilized, they are arranged in a parallel array as shown in FIGS. 4 and5 so that the light incidence surfaces of all the main bodies 2 define alarge surface 3A. Then light rays which are incident on the largesurface 3A from all directions are changed in directions of propagationwithin the main body and emitted out of the main body in directionsalmost perpendicular to the surface 3A.

Next the input of light rays through the light incidence surface 3 intothe main body 2 will be considered. It is assumed that the atmosphere ormedium surrounding the main body 2 be the air with n2=1 and the mainbody 2 is made of an acrylic resin with n=1.491. Then, since

    nl·sin δ.sub.0 =n2·sin 90°

    1.491·sinδ.sub.0 =1·sin 90°

Therefore,

    δ.sub.0 =sin.sup.-1 (sin 90° /1.491)=42.12°

Therefore, when viewed at a sectional plane, various light rays in airwithin an angular range of δ₀ X 2=84.24° can enter the main body 2 andare transmitted therethrough by reflections at the reflecting surfaces5a and 5b.

FIG. 7 shows a device for assisting the input of light rays into themain body 2 of the device for changing the directions of light rays.This device serves to reduce the quantity of said material of the mainbody 2 as much as possible so that the device for changing thedirections of light rays can be made light in weight and fabricatedeconomically. The device comprises mirrors 7 extended from the oppositesides of the light incidence surface 3 in such a way that they convergetoward the incidence surface 3. Incident light rays from variousdirections are reflected by the inner surfaces of the mirrors 7 anddirected to the incidence surface 3.

As described above, the reflecting surfaces 5a and 5b are convergedgradually in the direction away from the light incidence surface 3, butit is to be understood that the reflecting surfaces need not be opposingflat reflecting surfaces.

In an embodiment shown in FIG. 8, a circular light incidence surface 3Mis merged with a conical reflecting surface 5M so that a main body 2M isin the form of a frustum of cone.

In an embodiment as shown in FIG. 9, a main body 2N is in the form of ahexagonal prism and the reflecting surfaces 5N are defined by theinclined surfaces of the hexagonal prism. In addition, any prism havingany cross sectional configuration may be used.

In both of the embodiments shown in FIGS. 8 and 9, a light ray entersthrough the light incidence surfaces 3M and 3N and undergoes repeatedtotal internal reflections in a manner substantially similar to thatdescribed hereinbefore with reference to FIG. 1 and is emitted out ofthe main bodies 2M and 2N. In this case, it should be noted that a lightray propagates along three-dimensional path.

In the above-described embodiments, the light rays which undergosuccessive total reflections inside the main body 2, 2M or 2N areemitted out of the main body with a diverging angle β as shown in FIG.10 so that the quantity of light rays in parallel with the optical axisis not so great.

In order to overcome this problem, in an embodiment as shown in FIG. 11,optically transparent auxiliary elements 9 each having a triangularcross sectional configuration are attached to the outside surface of alight emitting portion of the main body 2. The light rays which areemitted from the main body 2 with a wide diverging angle pass throughthin air layers between the main body 2 and the auxiliary elements 9 andthen are reflected or refracted at least once by the reflecting surfaces10 or the auxiliary elements 9 after the light rays enter the latterwhereby the directions of propagation of light rays are changed to thosesubstantially in parallel with the optical axis when emitted from themain body 2. To this end, the reflecting surfaces 10 diverged rearwardlyin the direction opposite to that of the light incidence surface 3. Thereflecting surfaces 10 may be formed of reflecting films which, forinstance, are fabricated by a vacuum deposition process using aluminumThe auxiliary elements 9 are made of solid material. Instead, onlymirrors may be provided at the positions of the reflecting surfaces 10.In the case of providing the auxiliary elements 9 for the main body 2 ofFIG. 2, the elements are in the form of a plate of triangular crosssection, while for the main bodies 2M, 2N of FIGS. 8 and 9, they takethe form of an annulus encircling the main body.

Auxiliary elements 9M shown in FIG. 12 are different from those shown inFIG. 11 in that the surfaces of the auxiliary elements 9M which are madeinto contact with the main body 2 are formed with sawtooth portions 11.An air layer is formed between the sawtooth portion 11 and the main body2, whereby, as shown on an enlarged scale in FIG. 13, the light rayswhich are emitted out of the main body 2 into the air layer includeincreased components in parallel with the optical axis. Therefore, inorder to fully utilize such components, the sawtooth surfaces of theauxiliary element 9 receive the light rays emitted from the main body 2substantially at right angles therewith or in the directions almostparallel with the optical axis. When the light rays are emitted out ofthe auxiliary element 9M, its components parallel with the optical axisare increased.

In an embodiment as shown in FIG. 14, an auxiliary element 9N consistsof a lamination of a plurality of relatively thin layers. Each layer ofthe auxiliary element is gradually increased in thickness in thedirection away from the incidence surface 3 whereby, as shown in FIG.15, components of the light rays which are in parallel with the opticalaxis are gradually increased as the light is transmitted through thelayer by reflections and emitted out of the layer to the surroundingmedium.

Unlike the main body as shown in FIG. 2, especially the prism-shapeddevice for changing the directions of light rays shown in FIG. 8 or 9 isadapted to receive the light rays from all arbitrary directions aroundthe whole circumference and to change the directions of the light raysthus taken in. A plurality of such main bodies can be also arranged orassembled into an array so that they may be utilized in a modesubstantially similar to that described above with reference to FIG. 4.

Such an embodiment is shown in FIGS. 16A and 16B. A plurality of mainbodies 2M (2N) are bundled or assembled in the form of a circular diskas shown in FIG. 16A or in any suitable shape. Innumerable light raysfrom all directions are rendered substantially parallel with each otheras shown in FIG. 16B by this assembly

In the case of the embodiment shown in FIGS. 16A and 16B, the surfacesof light incidence of the main bodies 2M are arranged in coplanarrelationship, but it is also possible that they may be arranged todefine a convex surface as shown in FIGS. 17A and 17B or alternativelyto define a concave surface as shown in FIGS. 18A and 18B. In the caseof the former, the light rays emitted from the main bodies convergewhile in the case of the latter the light rays emitted from the mainbodies diverge In these cases, the light rays confined in a solid anglein corelation with the concave or convex surface are projected.

In an embodiment shown in FIG. 19, the index of refraction of the mainbody 2 is gradually or stepwise decreased away from the optical axis0--0 toward the outer surface. As a result, the path of a light raywhich is repeatedly reflected and transmitted through the main bodybecomes non-linear.

In an embodiment as shown in FIG. 20, two main bodies 2a and 2b arearranged in opposite directions and a transparent connecting element 13is mounted on the end surface 4 of the first main body 2 and the surface3 of incidence of the second main body 2b. Therefore, the light raysemitted from the first main body 2a enter the connecting element 13, arereflected in the interior of the same, and then enter the second mainbody 2b. Thus, in this embodiment, the light rays are reversed indirection when being emitted to outside.

Unlike the embodiments described above, in an embodiment shown in FIG.21, a main body 2P has a surface of light incidence 3 and reflectingsurfaces 5c, 5d and 5e and the surface of incidence 3 also serves as areflecting surface The main body 2P has a rectangular cross sectionalconfiguration as a whole and a reflecting plate 14 is embedded in themain body 2P. Therefore, a light ray which enters through the surface ofincidence 3 into the main body 2P undergoes "rotating" reflections bythe reflecting surfaces 5c, 5d and 5e, the surface of incidence 3 andthe reflecting plate 14 and is emitted out of the main body 2P to thesurrounding medium when the light ray reaches one of the reflectingsurfaces at an angle of incidence smaller than a critical angle δ₀.

In an embodiment shown in FIG. 22, a main body 2Q has a pair of opposingnon-parallel reflecting surfaces 5f and 5h and also a pair of opposingnon-parallel reflecting surfaces 3 and 5q. A light ray which entersthrough the surface 3 of incidence into the main body 2Q, therefore,undergoes rotating reflections successively and is emitted out of themain body 2Q into the surrounding medium when the light ray reaches oneof the reflecting surfaces at an angle of incidence smaller than acritical angle δ₀ as shown.

In the cases of the embodiments shown in FIGS. 21 and 22, the surface 3of incidence permits a light ray at a predetermined angle of inclinationwith respect thereto to enter the main body and the reflection of thelight ray which has thus entered is reflected in a predetermineddirection of "rotation" so that no such effect is attained when a lightray is reflected and rotated in the opposite direction. A device forselecting the angles of incidence as shown in FIG. 23 can be used inconjunction with the above-described main body. The device for selectingthe angles of incidence (to be referred to as "a selector" for brevityin this specification) comprises a first transparent element 16a and asecond transparent element 16b. A light ray incident at an arbitraryangle of incidence on a surface 17 of incidence of the first element 16ais reflected by an inclined surface 18 as indicated by the solid lineand redirected toward the main body 2Ql, but the light rays indicated bythe broken lines pass through-the inclined surface 18 toward the secondmain body 2Q2. As described above, the light rays incident on thesurface 17 of incidence at various angles of incidence are so selectedby the selector as light rays propagating in one direction and the lightrays propagating in another direction whereby the main bodies of theembodiments shown in FIGS. 21 and 22 are utilized to change thedirections of propagation of light rays from any arbitrary directions.

The total reflection surfaces of the main body can be coated with areflecting film except at a portion through which the light rays areemitted out of the main body to the surrounding medium.

FIG. 24 is a diagrammatic view illustrating on a further enlarged scalea portion of the assembly in which a plurality of main bodies 2 arearranged in a parallel array as shown in FIGS. 4 and 5. As describedabove, when a light ray enters through the surface 3 of incidence intoany one of the main bodies 2, it undergoes repeated total reflectionswithin the main body 2 and then is emitted out of the main body 2 intothe surrounding medium. As described above, the incident light ray L isconverted into a light ray which is emitted out of the main body and hasan increased components parallel to the longitudinal direction of themain body relative to the incident light ray L. When the light raysemitted out of the one main body 2 enters the adjacent main body 2successively, the components parallel to the longitudinal direction ofthe main body 2 are gradually decreased as shown in FIG. 24 as it passesthrough one main body to another. It is therefore quite apparent thatsuch phenomenon is not desirable.

In order to prevent such undesired phenomenon, the assembly as shown inFIG. 25 can be used. According to this assembly, a plurality of mainbodies 2d which are arranged in a parallel array and directed in onedirection are inserted into the spaces defined between the adjacent mainbodies 2c which are arranged in parallel array and directed in the otheror opposite direction in complementary relationship. In this assembly, alight ray L, which is incident on the surface 3 of incidence of one mainbody 2c and enters the same, undergoes repeated total reflections withinthe main body 2c, is emitted out from the main body 2c and immediatelyenters an adjacent main body 2d which is oriented in the one direction.After undergoing repeated total reflections within the main body 2d, thelight is emitted out of the main body 3d into the surrounding mediumthrough the bottom surface of the main body 2d. Thus, the phenomenondescribed before with reference to FIG. 24 can be avoided.

In the case of the assembly of the main bodies 2c and members 2d asshown in FIG. 25, a suitable light control element can be attached to atleast one surface of the assembly. In the case of an embodimentillustrating such attachment of such light or optical control elements,as shown in FIG. 26, an optical control element in the form of alenticular lens 20 is attached to the surfaces 3 of incidence of themain bodies 2c. Further, another optical control element in the form ofa Fresnel lens 21 is attached to the bottom or light-emerging surfacesof the members 2d. It is possible to exchange the positions of suchlenticular lens and Fresnel lens or to eliminate a lenticular lens orFresnel lens. Furthermore, it is possible to superimpose a plurality ofsuch light control elements one upon another. Moreover, other lightcontrol elements can be used. When such light control elements areprovided, further controls of light rays in response to opticalcharacteristics of these light control elements can be made.

As described above, when the device for changing the directions of lightrays in accordance with the present invention is utilized, light raysfrom different directions and within a certain angular range, incidenton a stationary surface of incidence, can be caught and can subject themto repeated internal reflections therewithin, to convert the light raysinto light rays which are substantially in parallel with desireddirection. Furthermore, even when the direction of incident lightvaries, it is not needed to trail the incident light. Moreover, thethree-dimensional main body used in this invention can be fabricatedfrom a simple optically transparent material. Therefore, the device, inaccordance with the present invention is inexpensive and is free frombreakdowns. In addition, in the device in accordance with the presentinvention, a plurality of main bodies can be assembled into variousshapes to obtain further useful effects. When the devices in accordancewith the present invention are superimposed one upon another or bundled,further complex and useful effects can be obtained.

INDUSTRIAL APPLICABILITY

According to the present invention, it becomes possible to receivescattered light, diffused light, light emitted from various portions ofa light source having some size, light whose direction varies and so onto redirect it in a predetermined direction or project it with a desiredshape. Therefore, the present invention can be used for utilization ofthe solar energy, illumination control, transmission of images andpatterns and so on.

I claim:
 1. An assembly for changing the directions of light rays,comprising a plurality of three-dimensionally shaped main bodies each ofwhich is made of an optically transparent material and has a lightincidence surface and a light emerging surface; each main body havingreflecting surfaces for causing successive internal reflectionstherewithin of light rays which have entered thereinto through saidlight incidence surface; said reflecting surfaces having such profilesthat when the light rays undergo the successive internal reflections bysaid reflecting surfaces, the directions of said successively internallyreflected light rays are caused to have incident angles which at leastreach a critical angle with respect to said reflecting surfaces;portions of said reflecting surfaces at which said successivelyinternally reflected light rays reach angles equal to or smaller thansaid critical angle and surface portions adjacent to said portions ofsaid reflecting surfaces constituting said light emerging surfacethrough which the light rays whose directions are changed are emitted;all the light incidence surfaces of said plurality of main bodies beingarranged in a parallel array and in coplanar relationship with eachother, wherein each main body is in the form of a wedge-shaped platewhose thickness is gradually decreased from one side thereof to anopposite, other side thereof; an end face at said one side of saidwedge-shaped plate defining said light incidence surface; opposingsurfaces extended between said one and other sides of said wedge-shapedplate defining said reflecting surfaces; a portion of said wedge-shapedplate adjacent to said other side of said wedge-shaped plate being saidlight-emerging surface portion; and the adjacent wedge-shaped platesbeing arranged in parallel with each other, and further comprising atleast one member which is made of an optically transparent materialdisposed in a space defined between adjacent ones of said main bodies,each said member being another wedge-shaped plate for changing thedirections of light rays emerging from said light emerging surface andbeing oriented in such a manner that the thickness of each said memberis gradually decreased in a direction toward said light incidencesurfaces.
 2. An assembly for changing the directions of light rays asset forth in claim 14, and further comprising an optical control elementextending across a light-emerging surface of each said member.
 3. Amethod of converting light rays having various directions of a wideangular range into light rays with a smaller range of directions, themethod comprising the steps of:providing a transparent optical body inthe form of a wedge-shaped plate having opposite non-parallel majorsurfaces constituting reflecting surfaces, and a light incidence surfaceinterconnecting one ends of said reflecting surfaces, said reflectingsurfaces converging gradually in a direction away from said lightincidence surface; causing light rays having various directions to entersaid optical body through said light incidence surface; causing thelight rays, which have entered said optical body, to be internally andsuccessively reflected by said reflecting surfaces until saidsuccessively internally reflected light rays are caused to have anglesincident on the reflecting surfaces, which angles are equal to orsmaller than a critical angle with respect to said reflecting surfaces;causing the light rays, whose angles incident on the reflecting surfaceshave become an angle equal to or smaller than said critical angle, toemerge from within the optical body to the outside through a lightemerging surface portion of the optical body remote from said lightincidence surface, in such a manner that the light rays emerging will bewithin a smaller range of directions; and causing the light raysemerging from said light emerging surface portion to pass throughtransparent auxiliary optical means of wedge-shaped cross section anddisposed outside of and adjacent to said light emerging surface portionfor making smaller the range of direction of the light rays which havepassed through the auxiliary optical elements.
 4. A method as set forthin claim 3, wherein said auxiliary means is made up of a lamination of aplurality of relatively thin layers.